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Changing Paybacks, Slot Clubs

4 December 2003

By John Robison

Dear John,

I have just started reading your articles and I find them very absorbing from my perspective as a computer programmer/analyst (unemployed, however).

I read somewhere that the only way a casino can change a payout percentage is to physically change the chip inside a machine. But I wonder since everything is hooked up to a main computer, couldn't those chips be made to be remotely programmable so they wouldn't have to go through that trouble?

Related questions: Do casinos spread "hot" machines throughout or concentrate them where players congregate, as near change booths and entrances, in order to entice them? Do they change payout percentages often to keep players guessing?

Thanks and I'm really looking forward to learning more!


Dear Jimmy,

Thanks for the kind words about my articles.

Regulators do not allow slots to be reprogrammed remotely because they're afraid that the program might be tampered with on its way from the server to the slot. It took a while for them to accept CD-ROM based games and I'm not sure they've agreed on adequate protections to allow hard drive based games.

That said, I think remotely programmable games will become a reality in five or so years. Today's video slots do not have to be limited to playing just one game or just one of the games in its menu if it's a multi-game machine.

One of the biggest problems for slot directors is deciding how many of each game they should order. And one of the biggest problems for slot players is finding an available machine with the game they want.

The future slot machine will be a slot workstation. It will be able to play any game that the casino has licensed by downloading it from the casino's game server. The slot directory won't have the problem of not having enough of a hot new game and then having too many when the game cools off. And players will no longer have to go on treasure hunts through the casino trying to find their favorite games.

To answer your second question, most of today's slot directors order roughly the same percentage payback for all of their machines in a particular denomination. And today's slots are so entertaining, players don't need to see other players winning to keep them playing. They're going to keep playing because they want to get to the bonus round again.

Finally, casinos do not change payout percentages often. Payback chips cost about $1,000 (and I don't know if there's any trade-in allowed on used chips), plus changing the chip can be quite a ritual in some jurisdictions. In fact, in some jurisdictions the casinos themselves do not even have a key to the logic drawer and someone from the gaming commission would have to change the chip.

Best of luck in and out of the casinos,

Dear John,

Just a comment on the letter from Bill on 11/1/03: I've worked native casinos as controller for over five years and that is one of the comments that always have been made by our customers. Fact is, we almost have to have a direct mandate from God to change the payouts - NIGC and our local auditors would crucify us. In most cases, we don't even have control of the chips, the gaming commission does.

It is a perceived problem and one that we caused ourselves by having loud music or lights going off when a jackpot pays out in many cases. The problem arises that when you have fewer people playing (i.e., during the day or on slow nights), you have fewer loud noises and big lights!

The only way I know to avoid it is to cheat - have noises and lights all the time so nobody notices and that would be of questionable value.

An associated problems occurs with ticket-in/ticket out machines - the customer misses the gratification of being noticed and personally served by a slot attendant and security guard and all the resulting hullabaloo that occurs on a hand payout. Same goes for slot fills but that is more of a benefit for all involved.

Keep up the good work.


[Bill asked whether it was possible for the Native American casino in which he plays to reprogram its slot machines based on the time of day.]

Dear Harold,

Thanks for sharing your experience. As I've learned more and more about Native American casinos and how they're regulated, I've discovered that it's not the "Wild West" free-for-all that I thought it to be.

You bring up an interesting point about ticket-in/ticket-out machines that I hadn't considered. And if I may add to what you said: Because ticket machines have fewer handpays, players will see fewer machines locked up (and therefore fewer big winners) and may get the impression that the casino is not paying as well as it did before it installed the ticket system.

Thanks again,

My question is about slot club cards that you insert into a slot on the machine or an external box. It is known that these are player tracking systems. My specific questions are:

1. Do the slot club cards enable the casino to determine how much of your money has been put into the machine vs payback credits played?

2. Do the slot club cards in any way alter the payback?

3. Other than comps that are offered to club members, are there any other reasons to support or oppose the use of the slot club cards?

1. Yes, they should have enough data to determine how much money you put into the machine.

2. No. Using a slot club card has no effect whatsoever on payback.

3. Some people don't like the casino being able to track their movements throughout the slot floor. The problem is that the casino can't comp you if they don't know how much you played.

Best of luck in and out of the casinos,

Dear John,

I recently spoke to a "slot tech" working at a casino who indicated several things to me which I question.

He said that he had several slot machines close to the door that paid over 100 percent.

He also indicated that the chip that controlled the payout was very difficult to change and had a "cycle" burned into it so it could be audited by officials. That would negate the RNG that is supposed to be dynamically operational in the slots at any given time.

The slots also "pause" at certain times during play. What is happening when a slot "pauses" during play?


Dear Dale,

Let's take the statements one by one.

First, I've never heard of a slot machine that pays back over 100%. I have heard, however, of video poker machines that can pay back more than 100% when played with the proper strategy.

Most jurisdictions prohibit slot machines that pay back more than 100% because the machine is guaranteed to be a loser for the casino--and the state! Anyone who can spin the reels will be playing at 100%+ payback.

Most people don't play video poker machines with the proper strategy, however, so video poker machines usually end up paying back a few percentage points less than their payback with mathematically perfect play. As a result, 100%+ payback video poker machines are legal in many areas.

Second, depending on where you are, changing the payback chip in a slot machine could require a ritual no less elaborate than the Changing of the Guard at Buckingham Palace. In Nevada, all you need is a Manufacturers License and almost every casino has one. In some jurisdictions, the logic drawer is sealed with evidence tape and breaking the seal and opening the drawer can be done only by a representative of the gaming commission.

The physical act of swapping chips, however, is just a matter of popping out one chip and putting in the replacement.

Machines do have something called a cycle, but it is essentially meaningless. The cycle is simply the total number of outcomes possible. You calculate the cycle by multiplying the number of stops on each virtual reel.

Officials audit machines based on how many times a machine has been played and how much it has paid back. Knowing the probabilities of hitting the winning combinations and the number of spins played on a machine, we can calculate a range of paybacks in which we expect the actual payback of the machine to fall with a specified level of confidence. If the actual payback does not fall within the range, there may be something wrong with the machine.

For example, let's say a 97% payback machine has been played 1,000,000 times. Because the results on the machine are truly chosen at random, the actual percentage paid back by the machine probably won't be 97%, but it will fall in a range around 97%. We check the par sheet provided by the manufacturer and see that they've done the calculations to tell us that 90% of the time, this machine will have paid back between 95% and 99% after 1,000,000 spins. If our machine has paid back anywhere between 95% and 99% of the money played through it, we would consider the machine to working properly.

Finally, all slots are required to store some accounting information even if they lose power. It takes a few seconds to burn this information onto special memory chips that don't go blank when power is lost. The program running the slot machine is storing that accounting info on the chips when the machine "pauses."

Best of luck in and out of the casinos,

Hi, John,

Could you tell me what video slots are out for home use?

Thanks and I think your articles are great.


Dear Pat,

Thanks for the kind words about my articles.

Masque Publishing ( has four CDs of slots. Video games on the disc Slots from Bally Gaming include: Popeye, Movie Star Betty, Cash Encounters, Blondie Double Feature, and Rich & Famous. Their Slots II disc has 99 Bottle of Beer, Boxcar Bonus, Hot Hot Hot, and Play the Market.

Best of luck in and out of the casinos,

Send your slot and video poker questions to John Robison, Slot Expert, at

John Robison
John Robison is an expert on slot machines and how to play them. John is a slot and video poker columnist and has written for many of gaming’s leading publications. He holds a master's degree in computer science from the prestigious Stevens Institute of Technology.

You may hear John give his slot and video poker tips live on The Good Times Show, hosted by Rudi Schiffer and Mike Schiffer, which is broadcast from Memphis on KXIQ 1180AM Friday afternoon from from 2PM to 5PM Central Time. John is on the show from 4:30 to 5. You can listen to archives of the show on the web anytime.

Books by John Robison:

The Slot Expert's Guide to Playing Slots